2/3 x x - 1/4 = 7 3/4 ghi lời giải hộ tôi
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\(\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)=\left(x-2\right)\left(x+2\right)\)
\(\Rightarrow8x+16-5x^2-10x+4x^2+4x-8x-8=x^2-4\)
\(\Rightarrow-6x-x^2-8-x^2+4=0\)
\(\Rightarrow-6x-2x^2-4=0\)
\(\Rightarrow-2\left(3x+x^2+2\right)=0\)
\(\Rightarrow\left(x+1,5\right)^2-0,25=0\)
\(\Rightarrow\left(x+2\right)\left(x+1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x+2=0\\x+1=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-2\\x=-1\end{cases}}}\)
=> \(\frac{7}{10}.x=\frac{1}{4}\)
=> \(x=\frac{1}{4}:\frac{7}{10}\)
=> \(x=\frac{5}{14}\)
\(\frac{7}{10}.x=\frac{3}{4}-\frac{1}{2}\)
\(\frac{7}{10}.x=\frac{1}{4}\)
\(x=\frac{7}{10}:\frac{1}{4}\)
\(x=\frac{14}{5}\)
\(x^2+2\left(x+1\right)^2+3\left(x+2\right)^2+4\left(x+3\right)^2=0\)
\(\Rightarrow x^2+2\left(x^2+2x+1\right)+3\left(x^2+4+4x\right)+4\left(x^2+6x+9\right)=0\)
\(\Rightarrow x^2+2x^2+4x+2+3x^2+12+12x+4x^2+24x+36=0\)
\(\Rightarrow10x^2+40x+50=0\)
\(\Rightarrow10\left(x^2+4x+5\right)=0\)
\(\Rightarrow x^2+4x+5=0\)
\(\Rightarrow\left(x^2+4x+2\right)+3=0\)
\(\Rightarrow\left(x+2\right)^2=-3\)
Mà \(\left(x+2\right)^2\ge0\)với mọi \(x\)
Vậy...
\(a.\frac{19}{5}\cdot\frac{4}{7}+\frac{3}{7}\cdot\frac{19}{5}-\frac{4}{5}\)
\(=\frac{19}{5}\cdot\left(\frac{4}{7}+\frac{3}{7}\right)-\frac{4}{5}\)
\(=\frac{19}{5}\cdot1-\frac{4}{5}\)
\(=\frac{19}{5}-\frac{4}{5}=\frac{15}{5}=3\)
\(b.2\frac{2}{7}\cdot5\frac{2}{5}+\frac{16}{7}\cdot1\frac{3}{5}+\frac{1}{2}\)
\(=\frac{16}{7}\cdot\frac{27}{5}+\frac{16}{7}\cdot\frac{8}{5}+\frac{1}{2}\)
\(=\frac{16}{7}\cdot\left(\frac{27}{5}+\frac{8}{5}\right)+\frac{1}{2}\)
\(=\frac{16}{7}\cdot7+\frac{1}{2}\)
\(=16+\frac{1}{2}=\frac{33}{2}\)
\(c.\frac{3}{7}\cdot3\frac{3}{4}-\frac{3}{7}\cdot\frac{5}{4}-\frac{1}{4}\)
\(=\frac{3}{7}\cdot\frac{15}{4}-\frac{3}{7}\cdot\frac{5}{4}-\frac{1}{4}\)
\(=\frac{3}{7}\cdot\left(\frac{15}{4}-\frac{5}{4}\right)-\frac{1}{4}\)
\(=\frac{3}{7}\cdot\frac{5}{2}-\frac{1}{4}\)
\(=\frac{15}{14}-\frac{1}{4}=\frac{23}{28}\)
Chú ý: \(\cdot:\times\)
4x5x6/3x10x8=120/240=120:120/240:120=1/2 nha
~HT~
k cho mình nha
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(x - 1)2 = (x - 1)4
TH1. x - 1 = 1 TH2. x - 1 = -1 TH3. x - 1 = 0
=> x = 1 +1 => x = -1 +1 => x = 0+1
=> x = 2 => x = 0 => x = 1
Vậy x = 2 hoặc x = 0 hoặc x = 1
A : 3 - 2 = -x + 1/7
1 = -x + 1/7
x= 1/7 -1
x = -6/7
B: 4/5 + (-1/9) = 8/7 -x
31/45 = 8/7 -x
x= 8/7 -31/45
x=143/315
C: [x-1/3] =10
=> 10\(\le\)3x-1/3 \(< \)11
=> 30 \(\le\)3x-1 \(< \)33
=> 31\(\le3x\)<34
<=> 11\(\le x< 12\)
=> x=11
D: [ -x + 2/5 ] = 3,5 -1/2
[-5x+2/5]=3
=> 3\(\le\)-5x+2/5 <4
=> 15\(\le\)-5x+2 <20
=> 13\(\le\)-5x< 18
=> -3\(\ge\)x>-4
=> x = -3
2/3 x X = 31/4 + 1/4
2/3 x X = 8
x = 8 : 2/3
x = 12
kq x =12 nha
tick cho mk vs
thanks